The field of spectroscopic analysis or spectroscopy pertains to the study of the dispersion of light into different colors based on the component wavelengths of the light. By analyzing the absorption and dispersion of incident light and other radiation by matter, scientists are able to study various properties of the matter such as temperature, mass, luminosity, composition, etc. Optical instruments known as spectrometers are used to measure and study such light dispersion, and play an essential role in the study and design of various scientific monitoring devices, for example multi-spectral imaging (MSI) systems, hyper-spectral imaging (HSI) systems, and the like.
In a conventional spectrometer, incident light passes through a first linear opening or slit in a first mirror or optical lens. A beam of incident light passing through the slit illuminates a prism or a linear grating device. The grating device may have a series of vertically-aligned linear gratings which diffract the incident light into its component colors, with each color corresponding to a particular frequency band of the electromagnetic spectrum.
Spectrometers may include multiple slits, with the first slit positioned in front of the linear grating device to initially select light in a relatively narrow frequency band. The linear grating device spreads this portion of the light beam at different wavelength-dependent angles. A second slit in another mirror or lens may be positioned in front of a photon detection device to allow selective passage of a narrower band of the incoming light beam from the linear grating device. In this manner, a specific wavelength or set of wavelengths may be selected for spectral analysis. The photon detection device detects the intensity of light of the specific wavelengths. In some spectrometer systems the linear grating device may be rotated to receive and diffract light of different wavelengths. The photon detection device then transits an electrical signal describing the intensity of the detected light to a recorder which records the signal at the predetermined wavelengths.
In certain conventional spectrometer designs the second slit and the photon detection device described above may be replaced with a multi-channel position-sensitive device such as a Charged Coupled Detector (CCD) array. As noted above, conventional spectrometers typically use linear gratings in conjunction with linear aperture slits, and thus an additional dimension is ordinarily required to effectively spread the incident light beam. Position-sensitive detectors such as CCD arrays may eliminate the need for a linear aperture slit, but nevertheless may require the additional dimension in order to function properly. The added dimension may result in a relatively bulky spectrometer design, with the lower size limit of a typical spectrometer being on the order of a few centimeters.